We request funds to upgrade the console of an existing Varian Innova 800 MHz solution NMR spectrometer to an Agilent DD2 console, extending the capabilities and lifetime of an essential instrument for biophysical research at UT Southwestern. Several key components that are in good working order, including a passively-shielded 18.8 T superconducting magnet and a 1H{13C,15N} coldprobe with cryogenic system, will be retained. The upgrade will take advantage of technology developments that improve the sensitivity and performance of a broad range of macromolecular and chemical NMR experiments. Further, these replacements will improve the long-term durability of this instrumentation, with benefits to its utility and accessibility. Each of the four investigators sering as PI/co-PIs have established internationally-recognized research programs that use solution NMR to study systems of the utmost biomedical interest. Examples include studies of intracellular trafficking, environmental sensing, cytoskeletal structure and chromosome dynamics; all of these are externally-funded by federal, state and private sources. Collaborations by these researchers and the facility manager enable NMR-based research in over 16 other groups, further expanding the impact of this instrumentation. As the highest-field NMR instrument in this portion of the south-central U.S., this equipment has also provided essential data to researcher's off-campus. The equipment requested in this application will enable researchers to have access to the highest sensitivity, most reliable instrumentation that is essential for challenging studies of proteins and complexes that often have limited solubility o abundance, which traditionally complicate NMR analyses on other instruments. We are committed to providing a world-class environment for biophysical research and training at UT Southwestern. From a research standpoint, the PI and co-PIs view solution NMR as one of the most versatile approaches available for studies of biomolecular structure, function and dynamics. All four of groups pursue challenging applications and develop new methodology, leading to publications which advance our specific biological fields and provide new tools to the NMR community. This research also represents a critical element of the educational mission at UT Southwestern, allowing the training of graduate students and postdocs in this powerful biophysical approach. The impact is extended more broadly to other on- and off-campus groups, by collaboration or providing instrument access at affordable rates. All of these activitie are made possible by the UT Southwestern Biomolecular NMR Facility, leading us to propose upgrading one of its central components to ensure the long-term viability of this resource.